In a nutshell, what does 'notional concord' mean? Can you kindly cite an example?

Example: She is grammatically correct with 'them' for English lessons, but notional concord easily overcomes that, and 'it' = taking English lessons is an easy step in comprehension for the reader to take.

Notional concord is concord decided by the speaker's idea/perception rather than grammar. If the speaker uses 'a group of ladies are coming', he is using notional concord-- the perception that it is several individuals-- rather than the grammatically singular 'group'._________________Native English teacher at Mister Micawber's